Inserter

ABSTRACT

The invention relates to an inserter for an infusion set for intermittent or continuous administration of a therapeutical substance such as e.g. insulin. The inserter comprises a needle unit comprising a needle hub ( 2 ) and a carrier body ( 4 ), and a cannula housing ( 3 ). The cannula housing and the needle hub are releasably connected and when they are connected, the insertion needle ( 6 ) is placed inside the cannula ( 5 ). The carrier body guides the movement relative to the set housing between a retracted and an advanced position. When released the needle unit and the cannula housing are forced by a spring unit ( 13 ) to an advanced position where the needle and cannula are placed subcutaneously. The object of the invention is to provide a disposable inserter for an infusion set which inserter is easy and safe for the user to handle during use and to dispose of after use.

TECHNICAL FIELD

The invention relates to an inserter for an infusion set forintermittent or continuous administration of a therapeutical substance,such as e.g. insulin. The inserter comprises a needle unit comprising aninsertion needle and a cannula housing comprising a soft plastic cannulato be placed subcutaneously in a patient.

BACKGROUND OF THE INVENTION

EP 688232 B1 relates to a low-profile, angled infusion set comprising acannula housing with a soft plastic cannula to be placed inside the bodyof a patient. During insertion the cannula housing is locked to a needlehub and the insertion set is placed by hand i.e. the set does notcomprise an inserter.

US 2002/0077599 A1 concerns an inserter for a low-profile, angledinfusion set which inserter comprises an inserter housing having abottom wall, a retainer slidably connected to the inserter housing formovement between retracted and extended positions in a directionsubstantially parallel with the bottom wall. The inserter also comprisesa base member connected to the outer surface of the inserter housing.The retainer is adapted to releasably receive a cannula housing. Whenused the retainer 30 moves forward and causes the needle 27 and thecannula 26 to pierce the skin at a proper angle and enter into thesubcutaneous layer at a proper distance. The cannula housing 28 can thenbe released from the inserter assembly 10 by depressing the releasebutton 66. Afterwards the mounting pad 80 is secured to the skin and theneedle 27 is removed, thus leaving the cannula 26 in place.

This reference concerns a rather complex structure and the complexitynecessitates the use of two housing portions, an upper and a lower whichportions may be constructed of any suitable material, and can beretained together through screws (23, FIG. 5), interlocking tabs,adhesive, heat-staking or a combination thereof, or any other well-knownfastening means.

The inserter described in U.S. Pat. No. 6,293,925 B1 comprises aninjector and an insertion set. The injector is designed to place aneedle through the skin at a selected insertion angle and with acontrolled force and speed of insertion. The injector comprises aspring-loaded plunger having a head for receiving and supporting theinsertion set in a position with an insertion projecting outwardly fortranscutaneous placement through the skin of a patient. The plunger isdesigned for retraction and retention to a locked position with a drivespring compressed in a manner applying a predetermined spring force tothe plunger head. FIGS. 30 and 31 illustrate how the subcutaneousinsertion set 14 is assembled with the injector when preparing theinjector for use.

DESCRIPTION OF INVENTION

The object of the invention is to provide a simple, non-expensiveinserter for an infusion set which inserter would be easy and safe forthe user to handle during use and to dispose of after use.

The invention concerns a disposable, low-profile inserter for an angledinfusion set which inserter comprises a set housing, a cannula housing,a needle hub, a spring unit and a carrier body, where

-   -   the set housing is provided with guiding means on the internal        surface for securing the movement of the carrier body,    -   the cannula housing comprises a soft cannula to be placed        subcutaneously,    -   the needle hub comprises a needle for piercing of the skin,    -   the cannula housing and the needle hub are releasably fastened        to each other and when fastened to each other the needle is        adjoined the cannula; preferably the needle is placed inside the        cannula;    -   the carrier body is provided with guiding means on the external        surface which secures the movement relative to the set housing        (1) from a retracted to an advanced position,    -   the carrier body is connected to release means, and when the        release means are manipulated, the carrier body, the cannula        housing and the needle hub are forced by the spring unit to an        advanced position where the needle and cannula will be placed        subcutaneous when the user holds the device against the skin,    -   the needle hub and the carrier body are provided with        unreleasable interacting locking means.

“Adjoined” means that the needle is placed adequately close to thecannula to assure the subcutaneously insertion of the cannula whetherthe needle is placed inside, beside or around the cannula.

According to one embodiment of the invention the needle hub and thecarrier body are created as a single unit e.g. by molding together amovable part of the set housing and a needle hub or e.g. by fastening aninsertion needle directly to a movable part of the set housing.According to the present invention it is also possible to use aninfusion set known per se as for example the set known from EP 688232 B1forming an unreleasable connection between a carrier body and the needlehub where after the needle unit comprising the carrier body and theneedle hub are fastened in the set housing during production of theinserter. The unreleasable connection could be formed e.g. by gluing,welding or by mechanically locking the two units to each other.

In a preferred embodiment the unreleasable connection between thecarrier body and the needle hub is formed by making openings in a partof the needle hub which is covered by a solid part of the set housing,and by making corresponding projections in the carrier body. When theset housing is placed around the needle unit (“around” meaning thatmaterial of the set housing covers the needle unit on at least twoopposite sides) either the elasticity of the set housing will squeezethe two opposite sides together and thereby squeeze the needle hub andthe carrier body together, or the confined space created by two oppositesides of an essentially rigid set housing will force the projections ofthe carrier body and the openings of the needle hub together and form anunreleasable connection between the carrier body and the needle hub asthe openings of the needle hub and the projections of the carrier bodyfit perfectly together.

According to another embodiment of the invention the needle unit islocked to the inserter after use. When the needle unit is locked to theinserter after use it will be possible for the user to remove both theinserter and the needle unit by only grabbing the inserter, instead ofthe user holding on to both inserter and needle unit after use.According to the embodiment shown in FIGS. 1-3 the needle unit is lockedto the inserter because the needle unit can only move in a confinedspace. The confined space is limited by the U-shaped set housing onthree sides, by the guiding means of the set housing and the needle uniton two sides as the guiding means prevents sideways movements and by thestopper 12 which prevents the needle unit from moving forward beyond afixed point.

According to another embodiment of the invention it is possible to movethe needle unit back from the advanced position where the needle canpierce the skin of a patient to a retracted position in order todiminish the risks of getting into contact with the used needle.

According to another embodiment of the invention the lower part of theset housing—where the lower part of the set housing is the side closestto the user during insertion—could be prolonged and turned upward inrelation to the base line (the base line is a line parallel to theneedle but at a lower level where a “lower level” means a level closerto the user, normally the level provided by the lower side of the sethousing). This prolongation or projection of the lower part provides anappropriate contact between the skin of the patient and the inserter inorder to have the cannula inserted in a proper angle, and also theprolonged or projecting part lifts up the mounting pad to a properposition for contact with the skin.

The end of the projecting part should preferably pass beyond the lineformed by the needle/cannula in front of the end of the insertion needlewhen the needle unit is in a retracted position. This makes it necessaryto provide an opening in the prolongation in order for theneedle/cannula to be able to pass through. According to the embodimentof FIGS. 1-3 this is obtained by separating the projecting part into twolegs. In this embodiment the projecting part is formed as a mathematicalcontinuous curvature but it could also be noncontinuous, i.e. beingprovided with one or more breaks.

In another aspect of the invention the set housing is made out of asingle piece of material. That the needle hub housing is constructed ofone piece of material means that no screws or the like is needed toassemble or fasten the casing surrounding the carrier body and theinserter set. The set housing could be produced by molding, i.e.injection molding or by any other known technology. Also the set housingcould be produced as e.g. two halves which afterwards are glued orwelded together. The set housing could be made of plastic or metal orany other suitable material having the necessary mechanical properties.

The inserter according to the invention is of a simple construction andconsists of relatively few parts and thus it will be less expensive toproduce and assemble. This renders the inserter especially suitable foruse as a disposable product.

In yet another embodiment the set housing is formed of a single U-shapedpiece of material. The set housing is U-shaped which means that it isconstructed of a rectangular or elliptic piece of flat material which isbent in such a way that the ends of the material—seen from theside—forms two substantial parallel legs connected in one end with astraight or arched line, where the legs are not necessarily of the samelength. The material is of a bend form which does not mean that it isconstructed by bending; it could e.g. be molded in a bend form. When theset housing is U-shaped the part called the lower leg is the leg incontact with the user when the inserter is in position for insertion ofthe infusion device.

In another embodiment the set housing is formed as a piece of pipe witha rounded or poly-sided cut-through profile.

In yet another embodiment the spring unit is fastened to the set housingin a first position and to the carrier body or the needle unit in asecond position, where the first position is situated closer to thefront end of the set housing than the second position when the springunit is biased, where the front end of the set housing is the end of theset housing nearest the user during insertion. This feature will resultin that the carrier body and the needle hub which are forming a singleunit is pulled forward relative to the housing when the release meansare activated. The spring unit could be made of any material whichretracts to a relaxed unbiased position, preferably made of rubber,plastic or metal.

DESCRIPTION OF THE DRAWINGS

The invention is explained in greater detail below with reference to theaccompanying drawings wherein a preferred embodiment of the invention isshown.

FIG. 1 is an upper/side view of an embodiment of the inserter of theinvention with the infusion set in a retracted position;

FIG. 2 is an upper/side view of the inserter with the infusion set in anadvanced position;

FIG. 3 is an upper/side view of the inserter with the infusion set in anadvanced position where the cannula housing has been detached from theneedle unit;

FIG. 4 is an upper/side view of the needle unit attached to the cannulahousing;

FIG. 5 is a lower/side exploded view of another embodiment of theinserter with the infusion set;

FIG. 6 is an upper/side exploded view of the inserter shown in FIG. 5with the infusion set;

FIG. 7 is an upper/side view of the inserter shown in FIG. 5 where theneedle unit is detached from the cannula housing and in an advancedposition.

FIG. 8 is an upper/side view of a third embodiment of an inserter placedready for delivery;

FIGS. 9 a and b show an exploded view of the third embodiment;

FIG. 10 shows the carrier body of the third embodiment in a retractedposition ready for insertion;

FIG. 11 shows a side view of a fourth embodiment with C-formed springunits;

FIG. 12 shows the needle unit combined with the spring unit of thefourth embodiment seen from above/behind;

FIG. 12A shows a spring unit similar to the fourth embodiment seen fromabove/front;

FIG. 13 shows a fifth embodiment with a circular spring seen from theside A, from above B and from behind C;

FIG. 13A shows a secondary embodiment with a circular spring seen fromthe side;

FIG. 14 shows a sixth embodiment with an S-formed spring unit seen fromabove;

FIG. 15 shows a seventh embodiment with a coiled spring unit seen fromthe side in (A) a forward position and (B) a retracted position;

FIG. 16 shows an eighth embodiment with a flat spring in A: a forwardposition seen from the side, B: a forward position seen from the behind,C: a retracted position seen from the side, D: a retracted position seenfrom above.

FIG. 17 shows a ninth embodiment with a spring unit fastened to oppositesides of the set housing and the embodiment is shown in (A) a forwardposition seen from the side, (B) a retracted position seen from theside, (C) a forward position seen from above, (D) a retracted positionseen from above.

FIG. 18 shows a tenth embodiment of the inserter with a spiral springunit;

FIG. 19 shows a side view of an eleventh embodiment of an S-formedspring unit;

FIG. 20 shows a view from above of the eleventh embodiment of theS-formed spring unit.

FIG. 21 shows an infusions set which can be inserted with the inserterof the invention.

The inserter set of FIGS. 1-3 comprises a set housing 1, a needle unitwhich in this embodiment is constructed of a needle hub 2 comprising aninsertion needle 6 and a carrier body 4 unreleasably connected to theneedle hub 2, and a cannula housing 3 comprising a laterally projectingcannula 5.

The set housing 1 is provided with a release button 7 which button whenactivated will release the spring unit 13 and cause the needle unit 2, 4and the cannula housing 3 to move forward to an advanced position. Whenthe release button 7 is activated, a flexible part 8 of the needle unitis pushed down and released from a not shown stop. The flexible part 8is shown on FIGS. 2, 3 and 7 where the needle unit is in an advancedposition and on FIG. 4 where the needle unit is shown isolated from theset housing 1.

FIGS. 1-3 and 5-7 show an embodiment of the invention wherein the sethousing 1 is U-shaped having an upper leg 1 a and a lower leg 1 b. Inthis embodiment the upper and the lower leg are parallel and connectedin one end through a piece of material approximately of the same lengthas the height of the needle unit 2, 4. The distance between the upperand the lower leg 1 a, 1 b will depend on height and general shape ofthe needle unit 2, 4 connected with the cannula housing 3 and also thedistance between the upper and lower leg 1 a, 1 b should be sufficientto comprise the guiding means 9 a, 9 b, 9 c which keep the needle unit2, 4 and cannula housing 3 in place during traveling between theretracted and advanced position.

The guiding means of the set housing in FIGS. 1-3 comprises two oppositeand outward L-profiles 9 a standing up from the lower leg 1 b, flanges 9b extending downwardly from the upper leg 1 a and flanges 9 b extendinginwardly from side parts of the upper leg 1 a being in contact with thesides 9 e of the needle unit 2, 4. The corresponding guiding means onthe needle unit 2, 4 comprise at the bottom side of the needle unit 2, 4two inward L-profiles (not shown in figures) which profiles correspondto the outward L-profiles on the set housing 1, see FIG. 5, and on theupper side of the needle unit 2, 4 two flanges 9 d are standing up fromthe top side keeping contact with the upper leg 1 a and the flanges 9 b.

At the end of the lower leg 1 b two upwardly bend parts 10 are formed.These parts 10 indicate the correct insertion angle for the user whenthe user inserts the cannula. Also the parts 10 will assure that amounting pad 14 placed in connection with the cannula housing 3 will bein correct and ready position when the cannula 5 is inserted.

The essentially triangular profile 11 extending from the lower leg 1 bis provided for facilitating handling as the total functional inserterset is quite small and else can be difficult to handle if the user hasreduced dexterity.

The spring unit 13 that pushes the needle unit 2, 4 forward when therelease button 7 is activated, is shown in FIGS. 6 and 7. The springunit 13 is placed between the set housing 1 and the needle unit 2, 4 atthe closed end of the U-shaped set housing 1. The spring unit 13 isfastened to a protrusion 18 a at the back end of the needle hub 2 and toa protrusion 18 b on the inside of the set housing 1. The spring unit 13may be any suitable spring but in this embodiment the spring unit 13 ispreferably a coil spring which pushes the needle unit 2, 4 away from theset house ending.

The spring unit 13 could also be a flat spring placed between the sethousing 1 and the needle unit 2, 4 at the closed end of the U-shaped sethousing 1, or the spring unit 13 could form an elastic connectionbetween the front of the set housing 1 and the back of the needle unit2, 4 pulling the needle unit 2, 4 forward.

In order to control the forward movement of the needle unit 2, 4 whenthe release button 7 is used, the lower leg 1 b of the set housing 1 isprovided with a stopper 12. In the embodiment in FIGS. 1-3 the needleunit 2, 4 stops moving forward when a corresponding protrusion on theneedle unit 2, 4 hits the stopper 12. In the embodiment in FIGS. 5-7 twoflanges 9 f move in tracks 19 formed as grooves in the lower leg 1 b andthe stopper 12 a is provided as the flanges 9 f touches the end of oneor both of the tracks 19.

If there is no stopper 12 to stop the needle unit 2, 4 from movingforward, the needle unit 2, 4 will stop when the front of the needleunit touches the skin of the user. The use of a stopper 12 will make iteasier to control the dept of insertion, and also the stopper 12 canlock the needle unit 2, 4 to the set housing 1 making it possible toremove inserter and needle unit 2, 4 as a single item after use.

In another preferred embodiment the stopper 12 is created by the ends ofthe upper and lower legs 1 a and 1 b of a U-shaped set housing 1. Whenboth or one of the ends of the legs 1 a and 1 b are turned inwardly, theleg ends restrict the distance between the upper and the lower leg 1 a,1 b at the open end of the U-shaped set housing. When this distance isrestricted to less than the height of the needle unit 2, 4, the inwardlyturned leg ends perform as a stopper 12.

In FIG. 5 the needle hub 2 is shown detached from the cannula housing 3and the carrier body 4. In this preferred embodiment the needle hub 2comprises two openings 15 in the rear half which openings 15 correspondto two projections 16 on the carrier body 4. When the projections 16 areplaced in the openings 15, the needle hub 2 and the carrier body 4 arelocked relatively to each other in the horizontal plane (in thisembodiment the horizontal plane is the plane perpendicular to thecontact surfaces between the openings of the needle hub 2 and theprojections of the carrier body 4). When the needle unit 2, 4 comprisingthe joined needle hub 2 and carrier body 4 is placed in the set housing1, the legs 1 a and 1 b of the set housing 1 cover the needle unit 2, 4on two opposite sides and prevent movements in the vertical direction.

When the inserter set is produced and prepared for use, it will normallybe delivered to the user in packed, set and sterilized condition beingready for use. When the user opens the package, the needle unit 2, 4 isconnected to the cannula housing 3 forming the infusion set, and theinfusion set is in a retracted position. A mounting pad 14 is placed onthe lower side of the cannula housing 3 and the sticky side of themounting pad is covered with release paper. The user removes the releasepaper from the mounting pad and places the base part 1 b, 10 of theinserter against the skin in an adequate angle; where after the userpushes the release button 7.

When pushing the release button 7 the needle unit 2, 4 together with thecannula housing 3 are released and pushed forward to the advancedposition, and the cannula will be placed subcutaneously as the insertionneedle 6 placed inside the cannula 5 pierces the skin.

The cannula could be of a known type as for example described in EPpatent no. 688232 where the cannula 5 is arranged in a rectilinear borethrough the cannula housing 3. The cannula housing according to thisdocument comprises two guide openings and two locking openings inaddition to the through bore. These openings are symmetrically shapedabout a plane including the central axis of the through passageway andextending perpendicular to the rear side. The guide openings areelongated openings of a substantially square cross section whichopenings are adapted to receive mating guide pins 17 on a connectingneedle or connecting hub. In FIGS. 3, 5, 6 and 7 where the needle unit2, 4 is separated from the cannula housing 3 it is possible to see theguide pins 17 of the needle hub 2.

When the cannula 5 and the cannula housing 3 covered with the mountingpad 14 is in place, the user unlocks the cannula housing 3 from theneedle unit 2, 4 and removes the remains of the inserter set whichcomprises the set housing 1 and the needle unit which is locked to theset housing 1. In EP patent no. 688232 an appropriate releasableconnection between a cannula housing and a needle hub is illustrated andthe example is hereby incorporated by reference.

In order to dispose of the used inserter remains in a secure way, theuser can pull the needle unit 2, 4 back into a retracted position andreplace the inserter remains in the opened package.

After having disposed of the inserter and the needle unit the user canconnect the cannula housing 3 which is now fastened to the user's skin,to a connecting hub.

The connecting hub can be connected to a luer coupling member through ahose. Through the luer coupling it is possible to administer a suitabletherapeutical substance, such as insulin from a pump. The connecting hubcan also be a closing part with a suitable entrance for the insertingneedle of a syringe. Such a closing part can stay in position for uptill three days while the user can have medication, e.g. insulininjected through the entrance in order to reduce trauma to the skin.

The inserter set according to a third embodiment shown in FIGS. 8-10comprises a set housing 1, a needle unit constructed of a needle hub 2comprising an insertion needle 6 and a carrier body 4 unreleasablyconnected to the needle hub 2, and a cannula housing 3 comprising acannula 5.

In FIG. 8 it is shown how this embodiment could be delivered: the needleunit 2, 4 is in a relaxed, i.e. non-biased or just slightly biasedforward position and the needle is covered with a hard case top 20 whichhas to be removed from the device before use. The set housing 1 isformed as a piece of pipe with an oval cut-through profile. Opposite thehard case top 20 the set housing 1 is covered with a removable flatcover 21. The flat cover can be provided with an adhesive for assuringthe tight closure between the cover 21 and the set housing 1 or it canbe welded to the set housing, and any kind of cover which at the sametime has the necessary strength to resist transportation and can providehermetical sealing of the device will do. The needle unit 2, 4 isunreleasably connected to a handle 22 which handle on the lower side isprovided with a projection 23 for fastening of a spring unit 13 (seeFIGS. 9 a and 9 b). The upper side of the carrier body 4 is providedwith guiding means 9 d having the form of a rectangular plate, theguiding means 9 d of the carrier body 4 fit into guiding means 9 b ofthe set housing 1 having the form of downward L-profiles.

The combination of the L-profiles and the rectangular plate assures thatthe carrier body has limited possibilities for moving up and down, andis lead along the wall of the set housing 1 in a very controlled manner.The spring unit 13 in this embodiment consists of elastic in the form ofan O-ring. The spring is fastened to the lower front part of the sethousing 1 at the position p1 and the lower part of the carrier body 4 atposition p2. In this embodiment the spring unit 13 is fastenedbehind—and beyond—the carrier part of the carrier body 4 which causesthe carrier body 4 to get into a slightly tilted position when thespring is biased as only the lower part of the carrier body 4 is pulledforward by the spring unit 13, and this tilted position can lock orsupport the locking of the carrier body 4 in the retracted position asthe guiding means 9 d are provided with a protruding part 30 (see FIG.12, 15, 19, 20) on the rearmost half. When the spring unit 13 is biased,this protruding part 30 will be influenced by a downward force createdbecause the carrier body 4 is being pulled forward at a low point.

When the user is going to apply the device the needle unit 2, 4 isbrought to a retracted position (see FIG. 10) by pulling the handle 22either (1) until the projection 23 on the lower side of the handlepasses a raised part 24 on the inside of the lower part of the sethousing 1 or (2) until the protruding part 30 on the guiding means 9 dpasses the end of or an opening in the L-profiled guiding means 9 b ofthe set housing 1. Then the user places the upwardly bend parts 10against the skin and release the needle unit 2, 4.

When the user wants to release the needle unit 2, 4 from the retractedposition the user can push the two pressure points 7 together if theneedle unit is locked by (1) or the user can push down at 7 a if theneedle unit is locked by (2). Preferably there will be indicatedpressure points 7 a on both upper and lower side of the set housing 1 inorder for the user to apply oppositely directed finger pressures. Whenthe to points 7 are pushed toward each other the diameter of the housingperpendicular to a line between the pressure points is increased, and asthe guiding means 9 d on the upper side of the carrier body 4 are caughtin the inward L-profiles the projection 23 is lifted free of the raisedpart 24. This activates the spring unit 13 and causes the needle unit 2,4 and the attached cannula housing 3 to move forward to an advancedposition. When pushing down at 7 a the user pushes down the front end ofthe guiding means 9 d and disengage the protruding parts at the rear endof the guiding means 9 d from the means 9 b of the set housing 1, thisactivates the spring unit 13 and causes the needle unit 2, 4 and theattached cannula housing 3 to move forward to an advanced position.

In FIGS. 11 and 12 is shown a fourth embodiment with a different kind ofspring unit 13. The spring unit 13 of this embodiment is made of twoflat springs and each of them is formed as a C when the spring unit isunbiased. That the flat springs are formed as a C means that theycomprise only one convex curve, how the springs are shaped and fastenedat each end, 13 a and 13 b, of the curve will depend on the material andthe form chosen for the springs. The flat springs 13 are fastened to thebottom wall of the set housing 1 in such a way that the back end 13 a ofthe C-formed spring units 13 are stationary in relation to the sethousing 1. The front end 13 b of the flat springs rests against asurface 4 a of the needle unit 2, 4 or is fastened to the needle unit 2,4. In this embodiment the C-formed spring units 13 are placed betweenthe back end of the needle unit 2, 4 and the back end of the set housing1 and when the handle 22 is pulled back, the spring units 13 are biased,the two ends of the C-formed spring units, 13 a and 13 b, are broughtcloser together. When the release button 17 is activated the springunits 13 will return to the unbiased form and the needle unit 2, 4 willbe pushed forward.

In FIG. 12A is shown an embodiment of the flat springs 13 are fastenedto the top wall of the set housing 1 in such a way that the back end 13a of the slightly C-formed spring units 13 are stationary in relation tothe set housing 1. The front end 13 b of the flat springs rests againsta surface of the needle unit 2, 4 or is fastened to the needle unit 2, 4but the front end 13 b is in this embodiment fastened to the front partof the needle unit 2, 4 below the needle level.

How the flat springs are fastened to the set housing 1 at 13 a willdepend on which material they are made of as this influence theform—particularly the thickness—they are made in. If the flat springsare made of a plastic material the material where they are fastened tothe housing 1 can take almost any form if they e.g. are produced bymolding. If the material is of an adequate thickness a protruding part25 of the flat spring can be squeezed into an opening in the set housing1. If the flat springs are made of e.g. metal it would be more expensiveto form a protruding part 25 on the flat spring, in this case it wouldin stead be efficient to cut e.g. a three-sided rectangular slit in theflat spring which is to be fastened to the set housing 1 and form acut-out 26. This slit makes it possible to bend the cut-out 26 out ofthe surface of the flat spring and let it rest against the set housing1. When the flat springs are fastened to the set housing 1 either by aprotruding part 25 or by a cut-out 26 it will not be necessary toperform further fastening of the springs to the housing e.g. by welding,gluing or the like.

FIG. 13 shows a fifth embodiment of the inserter where the spring unit13 is formed of a circular spring. The rearmost part 13 a of thecircular spring unit 13 is stationary to the set housing 1 and the frontpart 13 b of the circular spring 13 is fastened to the needle unit 2, 4or to the handle 22 or is simply resting against the movable needle unit2, 4 or handle 22 in a slightly biased state. The spring unit 13 mightbe formed with a prolonged part 13 c lying along the bottom wall of theset housing 1. Such a prolonged part 13 c could be fastened anyway alongits length but preferably at a position p1 close to the front of the sethousing 1.

FIG. 13A shows an embodiment where the rearmost part 13 a of thecircular spring unit 13 is resting against the upper part (above needlelevel) of the set housing 1 and the front part 13 b of the circularspring 13 is fastened to the handle 22 by simply resting a speciallyformed part against the handle 22 in a slightly biased state.

FIG. 14 shows a sixth embodiment with a spring unit 13 formed as an Sand constituted of a flat spring made of metal or plastic. The frontpart 13 b of the S-formed spring is fastened to or rests against asurface 4 a of the needle unit preferably in a slightly biased statewhen the needle unit 2, 4 is in its foremost position; the rearmost endof the S-formed spring is fastened to the bottom of the set housing 1.Preferably the rearmost end is fastened to the housing by a prolongedpart 13 c which can be placed in a trail formed by two opposite andinward turned, upright L-profiles, fastened at the rear end e.g. by aprotruding part 25 of the spring unit 13 being pressed into an openingin the set housing 1, and at the front by a three-sided rectangular slit26 in the prolonged part forming a cut-out which can catch the frontedge of the set housing 1. When the handle and the needle unit arepulled back the two ends of the S are pressed together biasing thespring, and when the release button is activated the spring pushes theneedle unit 2, 4 forward.

The spring unit 13 according to the sixth embodiment could also beformed as the number 8, have more curves than an ordinary S or morecircles than the number 8.

FIG. 15 shows a seventh embodiment of the inserter where the spring unit13 is formed of a coiled spring. The rearmost part 13 a of the coiledspring unit 13 is stationary to the set housing 1 and the front part 13b of the coiled spring 13 is fastened to the needle unit 2, 4 or to thehandle 22 or is simply resting against a part of the movable needle unitor handle in a slightly biased state. The spring unit 13 might be partlyenclosed in a trail lying along the bottom wall of the set housing 1.Such a trail would preferably be made of the same material as the sethousing 1. The trail can consist of to walls rising from the bottom wallof the set housing 1, and the walls might be parallel, rounded inwardsor inclined toward each other. A part of the needle unit 2, 4 is formedas reaching downwards, and this part reaches down into and slides insidethe trail. The front end 13 b of the spring unit 13 is fastened to orrest against this part. When the handle 22 is brought to the retractedposition, this part will assure that the spring unit 13 inside the trailis biased by pushing the movable end 13 b of the spring unit 13 towardsthe stationary end 13 a.

FIG. 16 shows an eighth embodiment of the inserter where the spring unit13 is a circular or rectangular leaf spring. The back end 13 a of thisflat spring 13 is stationary to the set housing 1, and the back end 13 bis fastened or rest against a part of the top wall of the set housing 1.The front end 13 b is fastened to the lower side of the needle unit 2, 4e.g. at a position p2 (see FIGS. 9 a and 9 b).

FIG. 17 shows a ninth embodiment of the inserter where the spring unit13 is fastened to opposite walls of the set housing 1. In FIG. 17 thefront ends 13 b of the spring unit 13 is fastened to the side walls ofthe set housing 1, and the rearmost part 13 a of the spring unit 13 isfastened to or rests against the movable needle unit 2, 4 at a positionp3. In this embodiment the spring unit 13 forms a loop around a low partof the needle unit 2, 4, and does not actually touch the position p3when the spring unit is in an unbiased state. When the handle 22 ispulled back biasing the spring unit 13, the loop will be deformed andtightened around the low part of the needle unit 2, 4, and when therelease button is activated the needle unit 2, 4 will be pulled forwardby the spring unit 13 as the loop will return to its original form.Preferably this embodiment would be made of a metal wire or anothermaterial with similar characteristics.

It would also be possible to construct the spring unit 13 of a flatspring where the foremost part is resting against the position p3 andindicated in FIGS. C and D with a thin black line, and the rearmost partis fastened to the side walls of the set housing 1 at the rear positionof the side walls. In this case the flat spring could be made of metalor plastic.

FIG. 18 shows an inserter with a spiral spring 13 where one end 13 a ofthe spring is fixed to a bottom part of the needle unit 2, 4, and theother end 13 b is fixed to a hook or similar at the front part of theset housing 1. When retracting the needle unit 2, 4 the spiral spring isuncoiled, and when releasing the retainer the spring coils up and movesforward, causing the needle and cannula to pierce the skin at a properangle and enter into the subcutaneous layer at a proper distance.

A tension spring could be made into a compression spring by passing bothspring wire ends through the centre of the coils/turns of the spring tothe opposite end of the spring. When pulling the wire ends the springwill compress.

In FIGS. 19 and 20 is shown an eleventh embodiment the spring unit 13 ismade of two flat springs and each of them is formed as a slightly bendS. That the flat springs are formed as an S means that they comprise twoconvex curves. The flat springs 13 are fastened to the top wall of theset housing 1 in such a way that the back end 13 a of the S-formedspring units 13 are stationary in relation to the set housing 1. Thefront ends 13 b of the flat springs are fastened to the needle unit 2,4. In this embodiment the S-formed spring units 13 are placed betweenthe front end of the needle unit 2, 4 and the back end of the sethousing 1 and when the handle 22 is pulled back, the spring units 13 arebiased, the two ends of the S-formed spring units, 13 a and 13 b, arebrought closer together. When the release button 17 is activated thespring units 13 will return to the unbiased form and the needle unit 2,4 will be pushed forward.

FIG. 21 shows an infusions set which can be inserted with the inserterof the invention. The infusion set comprises an infusion part which willbe inserted with the inserter and a connector part which after insertioncan form the connection between e.g. an insulin pump and the infusionpart. In this embodiment the connector part is symmetrical around theplane formed by the two arms.

Most of the embodiments of the spring unit shown here are compressionsprings, except the third embodiment which is provided with a springunit constituted by an elastic O-ring and the tenth embodiment which isprovided with a spring unit constituted by a flat spiral spring; theseunits are tension springs. The ninth embodiment which is constituted bya round thread works both as a compression and tension spring.

Spring units can e.g. be made of steel and in plastic. Spring units inplastic would preferably be made of POM (Polyoxymethylene), and sethousing, hard case top and carrier body would preferably be made of PP(Polypropylene). If the spring unit and the carrier body are moldedtogether as one unit the preferred material would be POM.

In this description the expression “flat spring” comprises “leafspring”.

In stead of using a spring unit 13 to bring the needle unit 2, 4 from aretracted to a forward position it would be possible to use magnets.When using magnets repulsive magnets with an adequate repulsive force tomove the needle unit 2, 4 from a retracted to a forward position shouldbe chosen. One magnet is placed in the set housing 1 and another magnetis placed at the needle unit 2, 4 carrying the infusion device. Therepulsion between the magnets will force the needle unit 2, 4 in aforward direction when releasing the needle unit 2, 4 by activating arelease button. The magnets can be molded into the set housing and intothe needle unit respectively in order to protect and hide the magnets.Further the repulsive magnets should be made in different sizes in orderto avoid that the magnetic field changes.

FIG. 21 shows an infusion set comprising a connector part 40 and cannulahousing 3. The cannula housing 3 can be inserted with the inserteraccording to the claims. After insertion the insertion needle 6 of theinserter is removed together with the inserter and the connector part 40is placed in the shown position. In this embodiment the connector part40 is symmetrical around the plane which is parallel to the needle andcomprises the two arms 41 of the connector part 40. This connector part41 also comprises a connector needle 42 which needle penetrates abarrier layer in the cannula housing 3.

The connector part 40 can be connected to a luer coupling member througha not shown tube. Through the luer coupling it is possible to administera suitable therapeutical substance, such as insulin from a pump. Theconnector part can also be a sort of closing part with a suitableentrance for an inserting needle of a syringe. Such a closing part canstay in position for up till three days while the user can havemedication, e.g. insulin injected through the entrance in order toreduce trauma to the skin caused by repeated penetration of the skin.

1. An inserter for an infusion set comprising a set housing (1), acannula housing (3), a needle hub (2), a spring unit (13) and a carrierbody (4), where the set housing (1) is provided with guiding means (9 a,9 b, 9 c) on the internal surface for guiding the movement of thecarrier body (4), the cannula housing (3) comprises a soft cannula (5)to be placed subcutaneously, the needle hub (2) comprises an insertionneedle (6) for piercing of the skin, the cannula housing (3) and theneedle hub (2) are releasably connected to each other, and when they areconnected, the insertion needle (6) is adjoined to the cannula (5), thecarrier body (4) is provided with guiding means (9 e, 9 d, 9 f) on theexternal surface which guides the movement relative to the set housing(1) between a retracted and an advanced position, and the spring unit(13) is connected to release means (7) and when the release means (7)are activated, the cannula housing (3), the needle hub (2) and thecarrier body (4) are forced by the spring unit to an advanced positionwhere the needle (6) and cannula (5) can be placed subcutaneously;wherein the needle hub (2) and the carrier body (4) are provided withunreleasable interacting locking means.
 2. An inserter according toclaim 1, characterized in that the insertion needle (6) is placed insidethe cannula (5).
 3. An inserter according to claim 1 or 2, characterizedin that the needle hub (2) and the carrier body (4) are created as asingle unit.
 4. An inserter according to claim 1 or 2, characterized inthat the needle hub (2) comprises openings (15) in a part of the needlehub (2) which openings are covered by material of the set housing (1),and the carrier body (4) is provided with projections (16) correspondingto the openings (15) in the needle hub (2).
 5. An inserter according toclaims 1-4, characterized in that the needle unit (2, 4) comprising theneedle hub (2) and the carrier body (4) after insertion can be placed ina retracted position.
 6. Inserter according to claims 1-5, characterizedin that the lower base of the set housing (1) is formed with aprojecting part (10).
 7. An inserter according to claim 6, characterizedin that the projecting part (10) forms an angle with the longitudinaldirection of the insertion needle (6).
 8. An inserter according toclaims 1-7, characterized in that it comprises a stopper (12, 12 a). 9.An inserter according to claim 8, characterized in that the stopper (12a) consists of at least one end of a track (19) for a flange (9 f). 10.An inserter for an infusion set comprising a set housing (1), a cannulahousing (3), a needle hub (2), a spring unit (13) and a carrier body(4), where the set housing (1) is provided with guiding means (9 a, 9 b,9 c) on the internal surface for guiding the movement of the carrierbody (4), the cannula housing (3) comprises a soft cannula (5) to beplaced subcutaneously, the needle hub (2) comprises an insertion needle(6) for piercing of the skin, the cannula housing (3) and the needle hub(2) are releasably connected to each other, and when they are connected,the insertion needle (6) is adjoined to the cannula (5), the carrierbody (4) is provided with guiding means (9 e, 9 d, 9 f) on the externalsurface which guide the movement relative to the set housing (1) betweena retracted and an advanced position, and the spring unit (13) isconnected to release means (7, 7 a) and when the release means (7, 7 a)are activated, the cannula housing (3), the needle hub (2) and thecarrier body (4) are forced by the spring unit to an advanced positionwhere the needle (6) and cannula (5) can be placed subcutaneously;characterized in that the set housing (1) is made of a single unit ofmaterial.
 11. An inserter according to claim 10, characterized in thatthe insertion needle (6) is placed inside the cannula (5).
 12. Inserteras claimed in claim 10-11, characterized in that the set housing (1) isU-shaped.
 13. Inserter as claimed in claim 12, characterized in that thelower leg of the U-shape comprises a projecting part (10) forming anangle with a base line below and parallel to the needle (6). 14.Inserter as claimed in claim 10-11, characterized in that the sethousing is formed as a piece of pipe with a rounded or poly-sidedprofile.
 15. Inserter as claimed in claim 1 or 10, characterized in thatthe set housing (1) forms at least a part of the delivering packing forthe inserter.
 16. Inserter as claimed in claim 1 or 10, characterized inthat the set housing (1) is provided with a hard top (20).
 17. Inserteras claimed in claim 1 or 10, characterized in that the spring unit (13)is fastened to the set housing (1) in a first position (p1) and to thecarrier body (4) or the needle hub (2) in a second position (p2), andthe first position is situated closer to the front end of the sethousing (1) than the second position when the spring unit (13) isunbiased.
 18. Inserter as claimed in claim 1 or 10, characterized inthat the spring unit (13) is an elastic O-ring.
 19. Inserter as claimedin claim 1 or 10, characterized in that the spring unit (13) is fastenedto the set housing (1) in a first position and fixed to the carrier body(4) or the needle hub (2) in a second position, and the first positionis situated closer to the back end of the set housing (1) than thesecond position when the spring unit (13) is unbiased.
 20. Inserter asclaimed in claim 1 or 10, characterized in that the spring unit (13) isa flat spring placed between the back end of the set housing (1) and theneedle unit 2,
 4. 21. Inserter as claimed in claim 20, characterized inthat the spring unit (13) has the form of two convex curves placed oneach side of the needle unit (2, 4), and that each curve is fixed to theneedle unit (2, 4) at one end (13 b) and to the set housing (1) behindthe fixation to the needle unit (2, 4) at the other end (13 a) in theunbiased state.